There has been proposed the method for forming color images on a thermal transfer image-receiving sheet which is dyeable with a sublimation dye by using a thermal transfer sheet constituted of the sublimation dye as a recording agent and a substrate on which the sublimation dye is supported. In this method, the dye is heated using a thermal head of a printer as a heating means and transferred on the image-receiving sheet to obtain the color images. The thus formed color images are very clear and excellent in transparency because of use of the dye, and are therefore expected to provide high-quality images which are excellent in reproducibility of half tones and gradation. However, the dye tends to suffer from color fading when exposed to external stimulus such as light, which will result in occurrence of color fading on prints obtained using the dye.
In order to prevent occurrence of color fading of the prints, there has been used the method in which a protective layer is transferred from a protective layer transfer sheet onto an image-receiving sheet to protect images formed on the image-receiving sheet.
Patent Document 1 discloses a polyester resin for use in a protective film for sublimation-transfer image-receiving members which is produced by copolymerizing a monomer having an alicyclic skeleton with an acid component and/or a glycol component in an amount of 15 mol % or more, for the purpose of improving a sensitivity and an image storage property.
Patent Document 2 discloses a protective layer transfer sheet including a base sheet and a thermally transferring protective layer formed on at least a part of one surface of the base sheet, in which the protective layer is in the form of a laminate having at least two layers including a layer containing at least an acrylic resin as a main component and a layer containing a polyester resin as a main component which are successively formed on the base sheet in this order.